Zoo's Chimp Baby Boom Explained

The mystery surrounding the paternity of three baby chimpanzees at the Los Angeles Zoo was finally solved Thursday when DNA results were released.

Despite a vasectomy in 1996, Shaun, an 11-year-old chimpanzee, is definitely the father, zoo officials announced. He is responsible for the birth of all three chimps during the past year: Toshi, Jean and Jake.

The mystery began Jan. 31 when a female chimpanzee was born.

None of the zookeepers had noticed that her mother was pregnant. And none of the males to which the mother had access seemed a candidate for fatherhood. Three of them, including Shaun, had undergone vasectomies. Two others were thought to be too young for amorous advances. The sixth male was getting old and had never shown interest in the opposite sex.

But within a month, two more females were found to be pregnant.

Paternity was established after genetic tests on blood and hair samples from the babies, mothers and the males.

"Shaun is quite big and handsome," said zookeeper Vicki Bingaman. "Prior to these babies, he has never reproduced."